Covers of this type for automotive applications in dashboards have to be high quality, thus not only sized correctly, but also very high quality with respect to the surface structure and the imprimation edges.
Covers of this type are typically not only made from a front plate providing the actual cover function but also from a base element extending from the backside of the front plate in depth direction, so that the front plate and the base element together provide a three-dimensional cover which is stable enough by itself for handling and assembly purposes and in which additional functions can be integrated.
For this purpose, the front plate is typically made from transparent material and is covered with a light permeable layer on its front side which is only interrupted where a light permeable, in particular backlit portion, shall be provided in the cover. For this purpose, the non light permeable layer is initially applied fully covering the surface of the front plate and subsequently removed again in the desired portions e.g. through laser impact.
An additional function of this type is e.g. the configuration of pass-through openings extending in the depth direction of the cover, in particular of the base element of the cover which can be closed on the front side by the front plate or can also be left open.
The pass-throughs that are open on the front side are used e.g. for inserting switches, actuation knobs which themselves in turn can form a cover according to the invention or similar from the front side of the cover, while the blind hole channels that are closed on the front side by the front plate have other functions and typically are not only used for stabilizing the base element.
Thus, e.g. portions of the cover, e.g. particular blind holes are backlit from the backside of the cover e.g. by LEDs which are arranged in a respective position on a circuit board arranged behind the cover.
In particular when the portion to be illuminated in the front plate of the cover is relatively small and due to the extension into the depth of the cover, the illuminating LED is relatively far behind the front plate, e.g. 1 to 2 cm or more, the illumination effect on the front plate is too small.
For this purpose, it is known to arrange a typically pin shaped light conductor made from plastic material in the dead hole of the cover, wherein the light conductor bridges the distance between the illuminating LED and the front plate that is light permeable in this portion in order to let a greater light volume reach the front plate. The light conductor pins are thus typically made from a transparent light permeable plastic material and the light conductor effect typically includes that at the side surfaces of the light conductor pin that extend along the light conductor pin, a reflection of the impacting light occurs and the light is reflected back into the light conductor.
In this context, it is already known that the light conductor function of the light conductor pins is less when the light conductor pins are produced through filling the dead hole channel with transparent plastic material through an injection molding method, thus the light conductor pins are melted together on their entire lateral surfaces with the surrounding walls of the dead hole, thus of the base element of the cover.
A melting together of the front face surface and/or of the front portion of the side surfaces of the light conductor pin, in particular with the backside of the front plate however is essentially harmless since a pass-through of the light rays is particularly desirable at this location.
Therefore, it is known to produce the cover and the light conductor pins separately, in particular produce them through injection molding and subsequently insert the light conductors from behind into the dead holes that are open in the back, where they are typically interlocked through friction locking or form locking of light conductor pin and dead hole.
This, however, means high logistics complexity and assembly complexity since the cover and light conductor pins initially have to be produced separately, though also possibly in the same injection molding tool, subsequently the light conductor pins have to be removed from the injection mold, stored in an intermediary manner, shipped to the assembly location, aligned correctly with the dead hole channel and inserted into the dead hole channels. Whether this is performed manually or automatically, the complexity is very high, also for automated assembly in particular the investment for extraction devices, assembly devices, transport devices, storage devices, etc., in particular for the up to 20 light conductor pins or more per cover is very high.
Another problem in this context is that covers of this type with respect to the shape of the face of the front plate typically are not flat but have a camber which can not only be provided in one spatial direction but in two spatial directions as it is often the case for covers for the dashboards for motor vehicles.
Since, due to injection molding reasons, the camber of the face side of the front plate is typically also provided on the backside of the front plate in order to provide and even wall thickness of the front plate and the light conductor pins shall contact the backside of the front plate with its faces surface, this means that light conductor pins that are to be inserted into a cover of this type, which can also be 10, 20 or more light conductor pins are not identical with one another, but respectively slightly different with respect to length, camber of the face surface, positioning of the snap-locking elements in their longitudinal extension etc.
This means that the light conductor pins are not exchangeable among one another with respect to the particular dead hole channels and due to the small dimensions of the light conductor pins, thus a length of 1 to 2 cm and a transversal extension of a few millimeters, the existing differences between the light conductors are so small that they typically cannot be detected with bare eyes. When subsequently assembling the light conductor pins in the respective dead hole channels of the cover, this typically leads to mix-ups when the light conductor pins are not separated from one another right from the beginning according to their types and even then mix-ups still occur.
However, when an incorrect light conductor pin is pressed into a dead hole channel during assembly, this is additionally often not recognized during assembly since the physical differences between the particular light conductors are very small.
This error typically only becomes apparent later, either because the subsequent assembly of the cover configured with light conductors is not possible in a surrounding component or it comes to damages either at the cover or at the incorrectly used light conductor or at the receiving component surrounding the cover.
For vendors that deliver covers for a larger sub-assembly, this causes great difficulties when reject parts due to incorrectly inserted light conductor pins are not detected and an deficient part is delivered to the customer.